Magnetic recording and reading device

ABSTRACT

A magnetic recording and reading device includes a magnetic recording medium having at least one magnetic recording layer, a magnetic head enabling a data transfer rate of more than 50 MB/s and a recording density of more than 5 Gb/in 2  on the magnetic recording medium, and a R/W-IC. The magnetic head includes a recording head and a reading head. The at least one magnetic recording layer contains (1) at least one metal element selected from a first group consisting of Co, Fe and Ni as a primary component, and (2) at least two elements selected from a second group consisting of Cr, Mo, W, V, Nb, Ta, Ti, Zr, Hf, Pd, Pt, Rh, Ir and Si.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation of U.S. application Ser. No. 11/699,998, filedJan. 31, 2007, now U.S. Pat. No. 7,339,762, which is a continuation ofU.S. application Ser. No. 10/644,824, filed Aug. 21, 2003, now U.S. Pat.No. 7,177,115, which is a continuation of U.S. application Ser. No.10/115,917, filed Apr. 5, 2002, now U.S. Pat. No. 6,819,531, which is acontinuation of U.S. application Ser. No. 09/725,317, filed Nov. 29,2000, now U.S. Pat. No. 6,407,892, which is a continuation of U.S.application Ser. No. 09/377,189, filed Aug. 19, 1999, now U.S. Pat. No.6,266,210, the subject matter of which is incorporated by referenceherein, and is related to U.S. application Ser. No. 09/725,253, filedNov. 29, 2000, now U.S. Pat. No. 6,404,605, which is a continuation ofU.S. application Ser. No. 09/377,189, now U.S. Pat. No. 6,266,210, andis related to U.S. application Ser. No. 09/836,481, filed Apr. 18, 2001,now U.S. Pat. No. 6,324,035.

BACKGROUND OF THE INVENTION

The present invention relates to a magnetic disc device used incomputers, information storage devices and so on, a magnetic storagedevice used in such information home appliances as digital VTRs, and amagnetic recording, and, more particularly, to a magnetic recording andreading device suitable for realizing high-speed recording and reading,and for high-density recording.

Semiconductor memories, magnetic memories, etc., are used in the storageor recording devices of information equipment. Semiconductor memoriesare used in internal primary storage in the light of high-speedaccessibility and magnetic memories are used in external secondarystorages in the light of a high capacity, low cost and nonvolatileproperty. Magnetic disk devices, magnetic tapes and magnetic cards arethe main current in magnetic memories. A magnetic recording portionwhich produces a strong magnetic field is used in order for writingmagnetic information in recording media, such as magnetic disks,magnetic tapes or magnetic cards. Further, reading portions based on themagnetoresistance effect or the electromagnetic induction effect areused in reading magnetic information recorded at a high density. Inrecent years, for reading, the giant magnetoresistance effect and thetunneling magnetoresistive effect have also begun to be examined. Thesefunctional portions for recording and reading are both installed in aninput-output part which is called a magnetic head.

The basic configuration of a magnetic disk device is shown in FIGS. 10Aand 10B. FIG. 10A shows a plan view of the device and FIG. 10B shows avertical-sectional view of the device. Recording media 101-1 to 101-4are fixed to a hub 104 to be rotated by a motor 100. In FIG. 10B showsone example which comprises four magnetic disks 101-1 to 101-4 and eightmagnetic heads 102-1 to 102-8. However, the magnetic disk device maycomprise at least one magnetic disk and at least one magnetic head. Themagnetic heads 102-1 to 102-8 move on the rotating recording media. Themagnetic heads 102-1 to 102-8 are supported by a rotary actuator 103 viaarms 105-1 to 105-8. Suspensions 106-1 to 106-8 have function of thepressing the magnetic heads 102 against the recording media 101-1 to101-4 under a determined load, respectively. A given electric circuit isneeded for processing of reproduction signals and for inputting andoutputting of information. Recently, a signal processing circuit inwhich waveform interference at high-density is positively utilized, suchas PRML (Partial Response Maximum Likelihood) or EPRML (Extended PRML)which is an enhanced. PRML, has been adopted, contributing greatly to ahigh-density design. The signal processing circuit is installed in acircuit board on a cover 108, etc.

The functional portion for writing and reading information on a magnetichead assembly is comprises components shown in FIG. 11A, for example. Awriting portion 111 is comprised of a spiral coil 116 between magneticpoles 117, 118 which are magnetically connected with each other. Themagnetic poles 117, 118 are both composed of a magnetic film pattern,which are made of an NiFe alloy, etc., respectively. The reading portion112 comprises a magnetoresistance element 113 made of an NiFe alloy,etc. and an electrode 119 for applying a constant current or a constantvoltage to the element 113 and for detecting changes in resistance. Themagnetic pole 118, which is made of an NiFe alloy, etc. and serves alsoas a magnetic shielding layer, is provided between the writing andreading portions. There is further a shielding layer 115 underneath themagnetoresistance element 113. A reading resolution is determined by theclearance distance between the shielding layer 115 and the magnetic pole118 (serving also as another shielding layer). The functional portion isformed on a magnetic head slider 1110 (FIG. 11B) via an underlayer 114made of Al₂O₃, etc. Incidentally, the magnetic head slider, which isprovided with a protection layer made of hard-carbon, etc. on thesurface opposed to the magnetic recording medium, is supported by agimbal 1111 and a suspension 1113, as shown in FIG. 11B. The magnetichead slider moves relatively to the magnetic recording medium whilefloating from the medium surface and, after positioning in an arbitraryposition by an arm 1114 connected to a motor, realizes the function ofwriting or reading magnetic information via lead lines 1116 and 1115.With respect to the above function, there is also provided an electriccontrol circuit together with the aforementioned signal processing unitor on the head carriage.

A detailed structure of a recording medium is schematically shown inFIG. 12. As described in JP-A-3-16013, most of the conventionally usedrecording media are produced by forming a magnetic layer 123 made of aCo—Cr—Ta alloy, or a Co—Cr—Pt alloy, etc. on a non-magnetic substratemade of Al plated with an NiP alloy, a glass, a high-hardness ceramics,a polished Si or the like, or a plastic substrate 121 by the sputteringmethod, or the evaporation method, or the plating method, etc. Usually,an under layer 122 made of Cr, or a Cr alloy, etc. for orientationcontrol of the magnetic layer is often formed on the substrate.Furthermore, a protection film 124 made of diamond-like carboncontaining nitrogen and/or hydrogen, or SiO₂ or SiN or ZrO₂, etc. isprovided to ensure durability of sliding resistance, and a lubricatingfilm 125 made of perfluoroalkyl polyether having an adsorptive or areactive end group, or organic fatty acids, etc. is provided.

In addition to the magnetic recording device, magneto-optic recordingdevices that perform recording and reading on a magnetic recordingmedium through the use of light have also been put to practical use. Themagneto-optic recording devices are classified into one type in whichrecording is performed only by light modulation and another type inwhich recording and reproduction are performed by light with a modulatedmagnetic field. However, the both types greatly rely on heat whenrecording and reading. Therefore, according to such type of devices, itis impossible to perform recording and reading in high data transferrate and thus they have been adopted mainly in backup systems, etc.

The importance of a storage device is determined by its storage capacityand the speed during inputting-outputting operations. In order toincrease competitiveness of products, it is necessary for the storagedevice to increase capacity by higher recording density, higherrotational speed and higher data transfer rate than those of the priorart. Thus, an important problem to be solved by the present invention isto provide a device capable of recording and reading at a high datatransfer rate of not less than 50 MB/s and, more preferably, that at ahigh density of not less than 5 Gb/in². A magnetic recording mediumcapable of recording and reading at a high frequency and capable ofobtaining a high S/N ratio at a high density and a magnetic head capableof generating a sufficient magnetic recording field at a high frequencyare necessary for meeting the requirement.

In conventional magnetic recording media, there have been proposed andactually carried out to reduce noise by refining crystal grains in orderto obtain a high S/N ratio at a high density of about 1 to 3 Gb/in², andby promoting segregation of non-magnetic components at grain boundariesto reduce exchange coupling among crystal grains as being taught inJP-A-63-148411, JP-A-3-16013 and JP-A-63-234407 so as to make thecoercive squareness S* to not more than 0.85 and the rotationalhysteresis loss RH to the range of 0.4 to 1.3. Noise can be considerablyreduced by recording and reading at a data transfer rate of not morethan about 20 MB/s. However, when the magnetic recording was carried outon that film media of the prior art at a high frequency of not less than50 MB/s, thermal fluctuation effects in fine magnetic crystallines isremarkable due to weak exchange coupling among crystal grains and theapparent coercive force is high resulting in that it was impossible torecord on it accurately. Furthermore, even when recording is performedunder a large current with utilization of a modified recording circuit,etc., the magnetic recording transition region is widened due to a broadmagnetic recording field resulting in that noise increases and/orrecorded information is lost when it was allowed to stand for a longtime.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a low-noise magneticrecording medium composed of fine crystal grains which is capable ofrecording and reading at a high data transfer rate of not less than 50MB/s and further permits high-density recording at not less than about 5Gb/in², a recording and reading magnetic head with high readingsensitivity which is capable of sufficiently sharp recording on themedium, and a magnetic recording device of a high data transfer rate andhigh density which is realized by using the magnetic recording mediumand the magnetic head of the present invention.

In order to achieve the above object, the present inventors pushedforward studies on chemical compositions of magnetic recording media,deposition processes and technologies related to devices such asmagnetic heads, and found out that the following means are veryeffective.

There is proposed a magnetic recording medium with a magnetic layercomprising at least one metal element selected from the group consistingof Co, Fe and Ni as a primary component, at least two elements selectedfrom a second group consisting of Cr, Mo, W, V, Nb, Ta, Ti, Zr, Hf, Pd,Pt, Rh, Ir and Si, and at least one element selected from a third groupconsisting of La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb,Lu, Bi, Sb, Pb, Sn, Ge and B. According to the magnetic recordingmedium, it is possible to obtain a high S/N (signal-to-noise) ratio evenunder recording at high data transfer rate of not less than 50 MB/s andto reduce the absolute value of normalized noise coefficient per a unittransition √{square root over (Nd²)}−No²·√{square root over (Tw/(S₀·D))}(Nd: recorded media noise, No: DC erase noise, Tw: effective read trackwidth, S₀: isolated pulse output, D: recording density in the unit offlux change per inch) to not more than 2.5×10⁻⁸(μVrms)(inch)(μm)^(0.5)/(μVpp).

The invention can provide a magnetic recording device which can performrecording at a high data transfer rate of not less than 50 MB/s by usingthe above magnetic recording medium, a magnetic recording head and anR/W-IC having the following features; that is, the magnetic recordinghead assembly is given a total inductance reduced to not more than 65 nHbecause it has a magnetic core length of not more than 35 μm, because itis provided with a magnetic film with a resistivity exceeding 50 μΩcm ora multilayer film composed of a magnetic film and an insulating film inpart of the magnetic core, and further because it is mounted on anintegrated circuit suspension; and the R/W-IC produced using a processof a line width of not more than 0.35 μm and is capable of operating athigh frequencies. Furthermore, the magnetic recording device of thepresent invention can perform the reading of magnetic information at ahigh density of not less than 5 Gb/in² by using a magnetic head providedwith a read element having a giant magnetoresistance effect or atunneling-magnetoresistance effect and with an effective track width ofnot more than 0.9 μm.

Recording density can be increased about 20% by forming the magneticlayer of the magnetic recording medium through a non-magneticintermediate layer comprising at least one element selected from thegroup consisting of Cr, Mo, W, V, Nb, Ta, Zr, Hf, Ti, Ge, Si, Co, Ni, Cand B as a primary component

A magnetic recording and reading device of higher density can beprovided by performing magnetic recording immediately after heatapplication to a magnetic recording medium through the use of asemiconductor laser, etc. and performing reading with the aid of theabove giant magnetoresistance effect element or an element having atunneling-magnetoresistive thin film.

Furthermore, in order to shorten an access time and perform positioningwith higher accuracy, it is effective to adopt a rotary type actuator toposition the head in at least two stages of coarse and fine movementadjustments.

The present inventors pushed forward on read-and-write properties of amagnetic recording medium as shown in FIG. 12, which is fabricated byforming a magnetic layer of a Co alloy, etc., a protective layer of C—N,etc., and a lubricating layer of perfluoro-alkyl-polyether, etc., inthis order, directly on a non-magnetic substrate or via a non-magneticunderlayer which comprises at least one element selected from the groupconsisting of Cr, Mo, W, Ta, V, Nb, Ta, Ti, Ge, Si, Co and Ni as aprimary component, the above magnetic layer was formed by controllingfilm deposition conditions, such as substrate temperature, atmosphereand deposition rate, heat treatment conditions, compositions of magneticlayer or under layer, a thickness of each layer, crystalline, the numberof layers, etc. At a recording density of 3 Gb/in² and at 10 kprm, thesemagnetic media were evaluated through the use of a conventional magnetichead with the MR element as shown in FIGS. 11A and 11B on a conventionalmagnetic disk device as shown in FIGS. 10A and 10B. As a result, thepresent inventors found out that by giving the above magnetic layer of acomposition containing at least one metal element selected from thegroup consisting of Co, Fe and Ni as a primary component, and at leasttwo elements selected from a second group consisting of Cr, Mo, W, V,Nb, Ta, Ti, Zr, Hf, Pd, Pt, Rh, Ir and Si, it is possible to refinecrystal grains and reduce the exchange interaction among crystal grainsand also to reduce the absolute value of normalized noise coefficientper recording density to not more than 3×10⁻⁸(μVrms)(inch)(μm)^(0.5)/(.μVpp) even when recording and reading areperformed at a transfer rate of not more than 20 MB/s of conventionaltechnology. This effect was remarkable especially during low-pressure,high-temperature and high-rate film depositions or during filmdepositions at a high pressure and a low deposition rate. Under otherconditions, however, this effect was good enough by optimizingcompositions and combinations.

On the other hand, in order to record at a high rate of not less than 50MB/s, it was necessary to use an R/W-IC (Read and Write IC) which iscapable of a high speed processing by putting fine-pattern-width for notmore than 0.35 μm to partial use at least and, in addition, it wasnecessary to develop a magnetic recording head structure capable ofgenerating a strong magnetic recording field at a high rate in responseto this fast driving current. In order to prevent the deterioration offast signals, it is important that the IC be installed in a position asclose to the head as possible and it was desirable to reduce thedistance to not more than 2 cm. The present inventors examined magneticpole and head structures and materials for magnetic poles, and developeda magnetic head assembly with a total inductance reduced to not morethan 65 nH in which the magnetic core length l₁ of a magnetic recordingcore composed of the lower magnetic pole 118 and the upper magnetic pole117 in FIG. 11A is not more than 35 μm, and which is provided with amagnetic film with a resistivity exceeding 50 μΩcm or a multilayer filmcomposed of a magnetic film and an insulating film in part of themagnetic poles composing the magnetic core, and which is mounted on asuspension 113 with an integrated conductive line through insulator1116. Recording magnetic fields obtained by this magnetic head wereevaluated with the aid of a magnetic field SEM, MFM, etc. As a result,the present inventors could ascertain that a sufficient magnetic fieldcan be generated even at a data transfer rate of not less than 50 MB/s,and found out that recording at a transfer rate of not less than 50 MB/sis, in principle, possible. Materials for magnetic poles with aresistivity exceeding 50 μΩcm include, for example, NiFe-base alloys,such as 42Ni-57Fe-1Cr, 46Ni-52Fe-2Cr, 43Ni-56Fe-1Mo, 51Ni-47Fe-2S and54Ni-43Fe-3P, and amorphous magnetic alloys, such as CoTaZr and CoNbZr.Examples of multilayer film composed of a magnetic film and aninsulating film include a multilayer film composed of 89Fe-8Al-3Si andSiO₂ and a multilayer film composed of 80Ni-20Fe and ZrO₂.

When recording and reading on the above medium at 50 MB/s through theuse of the magnetic head and circuit of the above construction,satisfactory recording was incapable due to a bad overwritecharacteristic, etc. and besides noise increased twice or three times.Thus, it became apparent that further ideas are necessary for ensuringrecording and reading both in high-density and high data transfer rate.Here, signals were read through the use of a conventional MR readelement with a narrow track width of 2 μm.

The reason for the above phenomenon was examined. The present inventorsconsidered that the above phenomenon is due to a bad frequency responsein the recording characteristic of the medium. Therefore, the cause wasanalyzed by performing a simulation through the use of a super computer,etc. and as a result, it became evident that there is a problem inthermal fluctuations of magnetization and spin damping during recordingprocess. Therefore, studies were carried out on medium additives capableof optimizing thermal fluctuations and damping coefficient. As a result,the present inventors found out that by adding at least one elementselected from a third group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu,Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Bi, Sb, Pb, Sn, Ge and B to thecomposition of the above medium, it is possible to reduce the absolutevalue of normalized noise coefficient per recording density to not morethan 2.5×10⁻⁸ (μVrms)(inch)(μm)^(0.5)/(μVpp) even when recording isperformed at 50 MB/s. This effect was observed when the above elementswere added in amounts of not less than 0.1 at %. However, their additionin an amount of 1 at % is sufficient. Addition in amounts of not morethan 15 at % was undesirable because of a remarkable decrease in output.Furthermore, the effect was remarkable when rare earth elements wereadded. The above effect was also ascertained in what is called agranular type medium in which a non-magnetic substance, such as SiO₂ andZrO₂, and a magnetic material with a high crystalline anisotropyconstant, such as CoPt and CoNiPt, were simultaneously formed bysputtering and the magnetic material with a high crystalline anisotropyconstant was precipitated and dispersed by heat treatment at atemperature of about 300° C. to obtain the above composition.Furthermore, in a case where the above magnetic layer is made of anamorphous magnetic substance, the magnetic layer often has perpendicularanisotropy. However, the same effect was also observed in this case.Furthermore, in any of these instances, when the above magnetic layerwas formed via a non-magnetic intermediate layer containing at least oneelement selected from the group consisting of Cr, Mo, W, V, Nb, Ta, Zr,Hf, Ti, Ge, Si, Co, Ni, C and B as a primary component, noise could beremarkably reduced because of statistical addition of signals and thiswas especially favorable for noise reduction. Furthermore, what isespecially noteworthy is that by reducing the magnetic core length ofthe above magnetic head to not more than 50 μm, a sharp and strongmagnetic field could be generated with increased efficiency andrecording on a medium with a higher coercive force was possible. This ispreferable because higher densities can be obtained. Furthermore, byinstalling the above R/W-IC near the suspension, the rise time of arecording magnetic field could be made further shorter. This permittedsharp recording and enabled medium noise to be relatively reduced.Therefore, this is more preferable.

In order to perform recording and reading at a high density of not lessthan 5 Gb/in², it was necessary to perform the reading of magneticinformation through the use of a magnetic head having an effectiveread-track width of not more than 0.9 μm with giant magnetoresistiveeffect or tunneling-magnetoresistive effect, and performs the reading ofmagnetic information at a high density of not less than 5 Gb/in². Byperforming reading like this, a signal-to-noise ratio of not less than20 dB of the device necessary for the operation of the device wasobtained with the aid of the signal processing method and it wasnecessary to combine the magnetic head with signal processing such asEPRML or EEPRML, trellis coding, ECCs, etc. Incidentally, the giantmagnetoresistive element (GMR) and tunneling magnetic head technologiesare disclosed in JP-A-61-097906, JP-A-02-61572, JP-A-04-35831,JP-A-07-333015, JP-A-02-148643 and JP-A-02-218904. An effective trackwidth of not more than 0.9 μm was realized by putting lithographytechnology based on an i-line stepper or a KrF stepper, FIB fabricationtechnology, etc. to full use.

The above system was a very epoch-making product as a magnetic disk.However, the present inventors found out that recording can be assistedby instantaneously heating a medium to the temperature range of fromabout 50° C. to 250° C. with a magnetic head provided with aheat-generating portion and thereby reducing the coercive force at ahigh frequency, and that this idea is further effective. In other words,in this system the load put on the recording portion and the materialfor recording magnetic poles could be reduced, and recording at a highdensity of not less than 5 Gb/in² and a high data transfer rate of notless than 50 MB/s was possible even with a recording track width of notmore than 0.9 μm and even when a magnetic pole material with asaturation magnetic flux density of 1 T was used. Thus, this wasespecially advantageous.

With respect to this effect, access time can also be shortened byperforming magnetic recording immediately after heat application to amagnetic recording medium and performing reading with the aid of theabove giant magnetoresistive element or element having atunneling-magnetoresistive effect. This is further preferable.

Furthermore, by using a semiconductor laser chip as the aboveheat-generating portion, an effective head volume can be reduced andhigh-speed positioning becomes possible. This is especially preferable.In addition, in order to shorten access time and ensure positioning witha higher accuracy, it is especially effective to position the head by arotary actuator method in at least two stages of coarse and finemovement adjustments.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows schematically the essential portion of a magnetic recordingmedium of the invention;

FIG. 2 shows schematically the essential portion of a magnetic headassembly of the invention;

FIG. 3A shows schematically a plan view of a magnetic recording deviceof the invention;

FIG. 3B shows a cross-sectional view of the magnetic recording deviceshown in FIG. 3A;

FIG. 4 shows schematically the essential portion of another magnetichead assembly of the invention;

FIG. 5A shows schematically the essential portion of a magnetic head ofthe invention;

FIG. 5B shows schematically the essential portion of another magnetichead of the invention;

FIG. 6A shows schematically the essential portion of magnetic write headpole structure of the invention;

FIG. 6B shows a cross-sectional view of the magnetic head pole structureshown in FIG. 6A;

FIG. 7A shows schematically the essential portion of another magneticwrite head pole structure of the invention;

FIG. 7B shows a cross-sectional view of the magnetic write head polestructure shown in FIG. 7A;

FIG. 8A shows schematically the essential portion of still anothermagnetic write head pole structure of the invention;

FIG. 8B shows a cross-sectional view of the magnetic write head polestructure shown in FIG. 8A;

FIG. 9 is a graph showing an effect of additive elements;

FIG. 10A shows schematically a plan view of a conventional magnetic diskdevice;

FIG. 10B shows a sectional view of the conventional magnetic disk deviceshown in FIG. 10A;

FIG. 11A shows schematically a partial sectional view of the essentialportion of a conventional magnetic head with write and read elements;

FIG. 11B shows schematically the conventional magnetic head shown inFIG. 11A; and

FIG. 12 shows schematically the essential portion of a conventionalmagnetic recording medium.

EXAMPLE 1

The magnetic disk of the invention is shown in FIGS. 3A and 3B. FIG. 3Ais a plan view of the device and FIG. 3B is a sectional view of thedevice. In the device of the invention, a recording medium 31 of theinvention, which will be described later in detail by referring to FIG.1, is fixed to a rotary hub 34 and rotated by a motor 310, and recordingis performed by a magnetic head 32, which will be described later indetail by referring to FIGS. 11A and 11B. The magnetic head 32 issupported by a rotary actuator 33 via an arm 311 and positioned fast andin a stable manner in a prescribed position of the rotating recordingmedium 31. In the drawing, the numeral 313 denotes a suspension andnumeral 20 denotes a gimbal. As shown in FIG. 2 which illustrates thedetails of the suspension 313, the suspension 313 used in this device isan integrated circuit suspension in which the wiring 21 and aninsulating layer are integrally formed on a plate spring through the useof the thin film technology so that the inductance of the wiring 21 isnot more than 15 nH. Lead lines 25 are connected to the wiring 21. Usualwiring of twist wires and wiring with an inductance of not less than 15nH, signals higher than 50 MB/s attenuate greatly. Thus, conventionaltypes of wiring could not been adequately put to practical use whencircuits of usual power were used. In a case where an R/W-IC portion 314was formed on the above integrated circuit suspension 313, in which thethin-film wiring and insulating layer were directly formed on the platespring, or an FPC for wiring, and the distance from the head was notmore than 2 cm, the attenuation of signals was not practically observedand an improvement in transfer rate of not less than tens of megabytesper second was observed compared to a case where an R/W-IC wasintegrated with a signal processing circuit and mounted on a circuitboard as conventionally. Thus, this was especially preferable. In thisexample of the invention, the distance was set at 1.5 and 1 cm.Incidentally, FIGS. 10A and 10B illustrates an example in which fourmagnetic disks 31-1 to 31-4 and eight magnetic heads 32 are mounted.However, at least one magnetic disk and at least one magnetic head maybe installed. In this example of the present invention, 1 to 30 headsand 1 to 15 magnetic disks were mounted on a casing 312 of magnetic diskdevice shown in FIG. 3.

The same prescribed electric circuit as conventional technology isrequired for recording information, processing read signals andinputting/outputting information. In terms of power consumption,however, a circuit using a CMOS is advantageous in comparison with acircuit using a Bi-CMOS and it is necessary to downsize circuitry inorder to perform recording and reading at a high rate of 50 MB/s. In allcases, therefore, it was necessary to adopt the patterning process fornot more than 0.35 μm in fabricating a part of the R/W-IC. In an actualcase where a patterning process for not less than 0.5 μm was adopted,good recording could not be performed. Incidentally, for channel LSIsfor signal processing, etc., it is necessary to reduce the circuit scalein order to reduce power consumption and a patterning process for notmore than 0.25 μm was adopted. In this example, a signal processingcircuit in which waveform interference in the age of high-density designis positively utilized was introduced and separated from the aboveR/W-IC. This signal processing circuit is called MEEPRML (ModifiedEEPRML), in which EEPRML (Extended Extended Partial Response MaximumLikelihood) is enhanced and the ECC function is also enhanced.Furthermore, in the case of perpendicular magnetic recording, readingwas performed by the PR5 signal processing method, etc. These componentswere installed in the circuit board on the cover 312, etc. The number ofrevolutions of the device was 10,000 rpm and the flying height was from26 to 28 nm in all cases.

The medium and magnetic head of the present invention, which compose themagnetic recording and reading device of the present invention, isexplained below in further detail.

First, the medium of the present invention is explained by referring toFIG. 1. The numeral 11 indicates a non-magnetic substrate which is madeof glass, NiP-plated Al, ceramics, Si, plastics, etc. and formed on adisk with a diameter of, for example, 3.5″, 2.5″, 1.8″ and 1″, a tape ora card. The numeral 12 indicates a non-magnetic underlayer which is madeof Cr, Mo, W, CrMo, CrTi, CrCo, NiCr, CoCr, Ta, TiCr, C, Ge, TiNb, etc.and contains at least one kind of element selected from the groupconsisting of Cr, Mo, W, V, Nb, Ta, Ti, Ge, Si, Co and Ni as a primarycomponent. The numeral 13 indicates a hard magnetic layer whichcomprises a crystalline magnetic substance of CoCrPtLa, CoCrTaCe,CoNiPtPri, CoPtNd—SiO₂, FeNiCoCrPm, CoFePdTaSm, NiTaSiEu, CoWTaGd,CoNbVTb, GdFeCoPtTa, GdTbFeCoZrRh, FeRhSiBi—N, CoPtIrSn—CoO, etc., whichcrystalline magnetic substance contains at least one metal elementselected from the group consisting of Co, Fe and Ni as a primarycomponent, at least two elements selected from a second group consistingof Cr, Mo, W, V, Nb, Ta, Ti, Zr, Hf, Pd, Pt, Rh, Ir and Si, and a leastone kind of element selected from a third group consisting of La, Ce,Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Bi, Sb, Pb, Sn, Geand B. This hard magnetic material has an absolute value of normalizednoise coefficient per recording density of not more than 2.5×10⁻⁸(μVrms)(inch)(μm)^(0.5)/(μVpp). The numeral 14 indicates a protectivelayer made of C to which N and H are added in combination, H-added C,BN, ZrNbN, etc. The numeral 15 indicates a lubricant ofperfluoro-alkyl-polyether having adsorptive or reactive end-groups suchas OH and NH₂, an organic fatty acid, etc. Between the non-magneticunder layer 12 and the hard magnetic layer 13, there may be provided asecond non-magnetic underlayer whose composition is further adjusted andwhich has a lattice constant capable of being more easily matched tothat of the magnetic film. When the above magnetic layer is divided by anon-magnetic intermediate layer which contains at least one elementselected from the group consisting of Cr, Mo, W, V, Nb, Ta, Zr, Hf, Ti,Ge, Si, Co, Ni, C and B as a primary component, noise decreases almostin proportion to the square root of the total number of magnetic layers.Therefore, this is more preferable.

Embodiments of medium of the present invention are explained below infurther detail. The magnetic disks of the present invention shown inTable 1 were obtained by first forming an underlayer on a glass disksubstrate with a diameter of 3.5, 2.5, 1.8 or 1 inch, then forming amagnetic layer of single-layer, two-layer or multilayer structure, a10-nm thick carbon protective film to which 10% N is added, and finallyforming a 5-nm thick lubricating film of perfluoro alkyl polyetherhaving —OH end group after surface treatment. The above underlayer ismade of the Cr alloys, Mo alloys, Ti alloys, W alloys, etc., whichcontains at least one element selected from the group consisting of Cr,Mo, W, V, Nb, Ta, Ti, Ge, Si, Co and Ni as a primary component. Theabove magnetic layer comprises a crystalline magnetic material ofCoCrPtGd, CoCrPtTaNd, CoPtDy—SiO₂, FeCoNiMoTaBi, NiFeCrPtGe, FeNiTaIrSm,etc., which crystalline magnetic material contains at least one metalelement selected from the group consisting of Co, Fe and Ni as a primarycomponent, at least two elements selected from a second group consistingof Cr, Mo, W, V, Nb, Ta, Ti, Zr, Hf, Pd, Pt, Rh, Ir and Si, and at leastone element selected from a third group consisting of La, Ce, Pr, Nd,Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Bi, Sb, Pb, Sn, Ge and B.

The above underlayer and magnetic layer were both formed by means of aDC magnetron sputtering device and the above protective film was formedin an N₂ gas atmosphere by the plasma-induced reactive magnetronsputtering method. Incidentally, in this example, parameters could bevaried independently of the underlayer and magnetic film each other andAr pressures of from 1 to 10 m Torr, substrate temperatures of from 100to 300° C. and deposition rates of from 0.1 to 1 nm/s were used. In theunderlayer, Cr, Ta, Nb, V, Si and Ge or alloys such as Co60Cr40,Mo90-Cr10, Ta90-Cr10, Ni50Cr50, Cr90-V10, Cr90Ti10, Ti95-Cr5, Ti—Ta15,Ti—Nb15, TiPd20, TiPt15, etc. were used as a single layer or two layerscomposed of dissimilar metal layers. Thus, samples of differentunderlayer compositions were prepared. The total film thickness of theunderlayer was from 10 to 100 nm, that of the magnetic layer was from 10to 100 nm, and that of the protective film was 10 nm. A multilayermedium 70 nm in thickness was also made by way of trial by depositingten layers of a combination of 5-nm thick CoCr₇Pt₆Gd₃ and 2-nm thick Ptlayers. The magnetic recording medium of the present invention wasevaluated by SEM or TEM and it was found that the magnetic layer ispredominantly composed of fine crystal grains with their average grainsizes of not more than 12 nm and not less than 8 nm for bothlongitudinal and perpendicular media.

TABLE 1 Ar Temperature Orientation Under sputtering of of layer pressuresubstrate magnetic Magnetic layer (nm) (nm) (mTorr) (° C.) layer 1CoCr₁₅Pt₈La₄ (25) CrTi (40) 2 250 in-plane 2 CoMo₁₅Pt₈Ce₁ (25) CrTi (60)2 250 in-plane 3 CoW₁₉Pt₄Pr₂ (25) CrTi (100) 2 250 in-plane 4CoCr₁₅Pt₈Ta₄Nd₄ (28) MoCr (10) 5 100 in-plane 5 CoCr₁₆Pt₁₀Ta₃Pm₅ (28)MoCr (20) 5 150 in-plane 6 CoCr₁₇Pt₁₀Ta₂Sm₃ (28) MoCr (30) 5 200in-plane 7 CoCr₁₃Pt₈V₅Eu₄ (35) CrV (10) 10 300 in-plane 8CoCr₁₆Pt₁₂Nd₂Gd₆ (35) Wsi (20) 10 300 in-plane 9 CoCr₁₅Pt₁₅V₄Tb₄ (35)CoCr (30) 10 300 in-plane 10 NiFe₁₀Cr₁₀Ir₄Dy₄ (26) NiCr (20) 1 209in-plane 11 FeNi₃₀Ta₅Th₄HO₂ (18) MoCr (30) 2 250 in-plane 12FeCr₁₉Pt₈Er₇ (29) CoCr (50) 2 275 in-plane 13 CoPt₂₀Ir₄Tm₁•SiO₂ (25) Ta(45) 1 250 in-plane 14 CoPt₁₅Ni₄Yb₈•ZrO₂ (25) V (30) 1 181 in-plane 15CoNi₂₂Pt₂₀Pd₄Lu_(0.5)•SiO₂ (22) Nb (50) 1 224 in-plane 16CoCr₂₃Pt₁₀Ti₅Bi₄ (100) TiCr (50) 2 174 perpendicular 17 CoCr₂₃Pt₁₀Ti₅Bi₄(100) TiCr (50) 3 160 perpendicular 18 CoCr₂₁Pt₈Hf₃Sn₄ (60) TiTa (50) 4156 perpendicular 19 CoCr₂₂Pt₈Pd₃Ge₁₅ (50) CoTaZr 6 140 perpendicular(50) 20 CoCr₂₂Pt₆Rh₂B_(0.1) (40) CoNbZr 6 106 perpendicular (50) 21CoCr₂₂Pt₆Si₂Sm₄ (40) TiPd (50) 6 191 perpendicular 22 CoCr₇Pt₆Gd₃/Pt(70) SiN (50) 5 151 perpendicular

Next, the magnetic head of the present invention is explained byreferring to FIG. 2 and FIG. 11A. A magnetic pole 117 of 43Ni-57Fe witha saturation magnetic flux density of 1.5 T and a resistivity of 50 μΩcmand another magnetic pole 118 of Ni80Fe20 with a saturation magneticflux density of 1.0 T and a resistivity of 28 μΩcm were formed by theframe plating method. Cu wiring of 2 layers and 15 turns was formedwithin a magnetic core length l₁ of 35 μm. The length of a record gap111 was 0.32 μm (material for the gap: Al₂O₃). Furthermore, the readelement was fabricated as follows. A magnetically free NiFe/Co film (6nm), a Cu film (2.5 nm), a magnetically fixed layer CoFe film (5 nm) anda CrMnPt film (25 nm) were first formed one after another and arectangular pattern was obtained. After that, a permanent magnet ofCo8D-Ni15-Pt5 (15 nm)/Cr (12 nm) and an electrode film of Ta (120 mm)were arranged on both ends of the pattern and a giant magnetoresistiveelement with a track width of 0.9 μm, which is determined by the gapdistance between the electrodes, was provided on a 2-m thick platedshielding film of Ni80-Fe20 by the i-line lithography technology,thereby giving this structure to the read element (shield gap: 0.3 μm,material for the gap: Al₂O₃). The magnetic head element provided withthis read element was formed on a slider made of Al₂O₃—TiC with a sizeof 1.0×0.8×0.2 mm³. Incidentally, the recording track width was trimmedto 1.1 μm from the floating surface side by the FIB (Focused Ion Beam)fabrication technology and a shaped rail structure was fabricated to thefloating surface of the head. In addition, to improve the anti-adhesiveproperty minute projections were provided at three points of thefloating surface and a C/Si protective film with a total thickness of 3nm was formed on the floating surface. As shown in FIG. 3, this head,along with an RW-IC 314 for which the scaledown process for 0.35 μm inthis example was adopted, was fixed with an adhesive to an integratedcircuit suspension 313 of the present invention on which a conductiveline pattern through an insulating film were formed by the thin filmfabrication process. A magnetic head assembly was thus obtained. As aresult of the foregoing, in the integrated circuit suspension of thepresent invention for a disk with a diameter of 3.5, 2.5, 1.8 or 1 inch,the total inductance of the head assembly measured from R/W IC terminalsat 10 MHz was 65, 63, 61 and 57 nH, respectively, not more than 65 nH.

Incidentally, heads with a magnetic core length l₁ of 25, 30 and 40 μmwere also made by changing the number of turns to 9, 11 and 13,respectively. When the magnetic core length was 40 μm, in the integratedcircuit suspension of the present invention for a disk with a diameterof 3.5, 2.5, 1.8 or 1 inch, the total inductance was as large as 75, 73,71 and 68 nH, respectively. In these cases, the overwrite characteristicat 50 MB/s was as low as 20 dB, sufficiently sharp recording could notbe performed, and noise was very large. Thus, these heads could not beput to practical use. From the above, it became apparent that it isnecessary that the magnetic core length be not more than 35 μm and thatthe total inductance be not more than 65 nH. Table 1 shows only cases inwhich goods results were obtained with an overwrite characteristic ofnot less than 30 dB. Furthermore, when the characteristic was evaluatedon a tunneling magnetic head with a read track width of 0.85 μm, made bythe technology stated in JP-A-02-148643 and JP-A-02-218904, quite thesame result was obtained. With a conventional MR head having the sametrack width for comparison, however, even in a case where the conditionof the device was evaluated through the use of a signal processingcircuit of the EEPRML type by the lithography process of 0.25 μm,sufficient read output and error rates could not be obtained. Thus, thisconventional MR head could not bear the evaluation.

The device characteristics of the present invention are described blow.A signal processing circuit of the EEPRML type by the lithographyprocess of 0.25 μm was used. In order to perform high-density, high datarate recording with high quality and a high signal-to-noise ratio forthe characteristic in each record track position, it is necessary toensure a strong and sharp recording magnetic field at a high frequencyand, at the same time, it is necessary to reduce the irregularity of thesaw tooth magnetic domains at record bit boundaries by reducing thecrystalline grain size in the medium and also reducing the exchangeinteraction among magnetic crystalline grains, to reduce the noise atbit boundaries that increases in proportion to recording density, and toensure an appropriate response to a high-frequency magnetic field byoptimizing the damping of magnetization during recording. Forcomparison, media were made without the addition of only the third groupof elements so that these media correspond to those given in Table 1. Onthe media of these comparative examples, when recording was performed ata transfer rate of not less than 20 MB/s, the absolute value ofnormalized noise coefficient per recording density increased abruptly at5 Gb/in² even when the above-mentioned head and R/W-IC were used. Whenrecording was performed at 50 MB/s, the absolute value of normalizednoise coefficient per recording density reached large values of from 10to 30×10⁻⁸ (μVrms)(inch)(μM)^(0.5)/(μVpp) and the bit error rate of thedevice was worse than 10⁻⁵. Thus, these medium could not be used forpractical use. In contrast, all the media of the embodiments shown inTable 1 had an absolute value of normalized noise coefficient perrecording density of from 1 to 2.5×10⁻⁸ (μVrms)(inch)(μM)^(0.5)/(μVpp),which are not more than 2.5×10⁻⁸ (μVrms)(inch)(μm)^(0.5)/(μVpp), and thebit error rate was better than 10⁻⁹ even under the conditions of both 5Gb/in² and 50 MB/s. Thus, it became apparent that these media of thisexample were especially preferable.

For the effect of the elements of third group to a medium, cases withadditives of from 0.1 to 15% were described in this example. However, asis apparent from FIG. 9 which shows cases with varied La contents of0.01, 0.1, 0.5, 1, 2, 10, 15, and 20 at % under the conditions of #1 ofExample 1, the signal-to-noise ratio in recording at 50 MB/s improvedremarkably. The effect is sufficient when the quantity of additives is 1at %. The output and signal-to-noise ratio decreased remarkably when thequantity of additives was not less than 15 at % and, therefore, this wasnot preferable. Furthermore, the effect was especially remarkable whenrare earth elements were added.

A medium of another embodiment was prepared under the same conditions asthose for the above first embodiment of Example 1 by dividing themagnetic layer into two layers by a non-magnetic intermediate layer,which contains as a main element at least one selected from the groupconsisting of Cr, Mo, W, V, Nb, Ta, Zr, Hf, Ti, Ge, Si, Co, Ni, C and Bsingly or Cr—Ti10, Mo—Cr10, WSi5, Ta—Si5, Nb—Zr10, Ta—Cr5, Zr—Hf10,Hf—Ti5, Ti—Si10, Ge—Pt5, Si—Ru11, Co—Cr30, C—N10, B—N10, etc. However,noise reduced to approximately 70% and the device operated adequatelyeven under the conditions of both 7 Gb/in² and 50 MB/s. Thus, the effectwas more remarkable. It is needless to say that the above effect doesnot depend on the diameter of a disk or forms of medium such as a disk,tape and card.

EXAMPLE 2

Another example of the present invention is explained by referring tothe conceptual drawing of a magnetic head assembly shown in FIG. 4. Fora magnetic head 42, first as recording elements, 40Ni-55Fe-5Cr with asaturation magnetic flux density of 1.4 T and a resistivity of 60 μΩcmwas used as the material for a magnetic pole 117 with a track width of0.6 μm and another magnetic pole 118 was formed from CoTaZr with aresistivity of 120 μΩcm in FIG. 11A. Track width fabrication wasperformed by trimming on the basis of the FIB technology as withExample 1. A record gap length of 0.25 μm (material for the gap:Al₂O₃-3% SiO₂) was selected, the magnetic core length l₁ was 30 μm, andan Al coil 116 of 2 layers and 12 turns was used. Furthermore, the readelement was fabricated as follows. A magnetically free NiFe/Co film (6nm), a CuNi film (2.5 nm), a magnetically fixed layer of CoFe/Ru/CoFefilm (6 nm) and an MnIr film (15 nm) were first formed one after anotherand a rectangular pattern was fabricated. After that, a permanent magnetof Co75-Cr15-Pt12 (10 nm)/CrTi (5 nm) and an electrode film of Nb (100mm) were arranged on both ends of the pattern and the above giantmagnetoresistive element with a track width of 0.5 μm, which isdetermined by the distance between the electrodes, was provided on a2.5-μm thick plated shielding layer of Ni80-Fe20 through an 0.45 μmthick shield gap 110 in FIG. 11A of Al₂O₃, thereby giving this structureto the read element (total shield gap: 0.20 μm, material for the gap:ZrO₂). A magnetic head 42 was obtained by forming this element on aslider made of Al₂O₃—TiC with a size of 1.0×0.8×0.2 mm³. The magnetichead assembly was obtained by mounting this head on an integratedcircuit suspension of the present invention of FIG. 4 in which leadpattern through an insulating layer were formed by the thin filmfabrication process.

In FIG. 4, with the assistance of a fine adjustment portion 43 ofelectromagnetic drive, etc. capable of position corrections of about 10μm at a high rate, a suspension 44 has the function of positioning amagnetic head 42 in the prescribed position of the recording medium at ahigh speed in collaboration with the rough movement function of a rotaryair actuator 45. For this reason, in Example 2, the R/W-IC of thisexample fabricated by the processes for 0.35 and 0.25 μm line widths wasmounted on a wiring FPC (Flexible Printed Circuit) installed adjacent toan integrated circuit suspension in which lead pattern was formed by thethin film process, and its distance from the head was 3, 2, 1.5, 1 and0.7 cm. Incidentally, a signal processing LSI of the EEPRML by thescaledown process for 0.25 μm was used. Incidentally, the fineadjustment portion 43 is not limited to a fine movement means of theelectromagnetic force drive type and may be a fine movement means of thepiezoelectric force drive type, magnetostrictive force drive type, etc.As a result of a comparison and examination, it was found that the typein which a multilayer piezoelectric device is used has the least adverseeffect on power consumption and the read element of GMR or MR. However,the other types also met required functions. Another disk device of thepresent invention was obtained by mounting this head assembly on amagnetic disk device of the present invention shown in FIGS. 3A and 3Band by using the media of 2.5″ and 1.8″ diameters shown in Table 1 andthe same circuit as in Example 1. In Example 2, combinations of 1 to 10media and 1 to 20 heads were used. Incidentally, a slider of shaped railstructure with three minute projections was used and a 3-nm thickprotective film of C—N—H was provided on the bearing surface. However,during the evaluation, the flying height of the magnetic head was 25 nmand the number of revolutions was 15,000 and 25,000 rpm.

In all the combinations, the device operated adequately in a conditionbetter than a bit error rate of 10⁻⁹ under the conditions of 10 Gb/in²and 50 MB/s. Thus, this effect was more remarkable. At 20,000 rpm,recording was severer and the device operated in a condition better thana bit error rate of 10⁻¹⁰ when the R/W-IC of the present invention basedon the process for a line width of 0.25 μm was used. This was especiallypreferable. Incidentally, for the distance between the R/W-IC of thepresent invention and the head of the present invention, the datatransfer rate could be increased to 50, 54, 54, 54 and 55 MB/S withdecreasing distance to 3, 2, 1.5, 1 and 0.7 cm, respectively. Distancesof not more than 2 cm were especially effective. It is needless to saythat this effect does not depend on the diameter of a disk or forms ofmedium such as a disk, tape and card.

EXAMPLE 3

A third example of the present invention is described below by referringto FIGS. 5A and 5B, FIGS. 8A and 8B and FIGS. 3A and 3B.

As shown in FIGS. 5A and 5B, a laser chip 52, 52′ of about 0.3 mm squarewas mounted on a position-correcting mount 51, 51′ of the piezoelectricforce type, electromagnetic force type or magnetostrictive force type.The laser chip thus mounted on the position-correcting mount was thenmounted on a head slider 50, 50′ as shown in FIGS. 5A and 5B to permitadjustments so that a recording and reading element portion 53, 53′ anda laser beam position 54, 54′ are located almost on the same recordtrack 55, 55′. An Al₂O₃—TiC slider of shaped rail structure with a sizeof 0.7×0.2 mm³ (FIG. 5A), provided with three minute projections, wasused and a 3-nm thick protective film of C—N was provided on thefloating surface. The volume including the laser chip (FIG. 5B) was1.0×0.9×0.2 mm³, and the distance over which corrections are possiblewas 20 μm maximum. Although the correction mechanism is not alwaysnecessary, the absence of this mechanism was not much preferable becauseof a low margin for reproducibility. Incidentally, the laser wavelengthwas 830, 780, 650 and 630 nm and the power was from 5 to 50 mW. Toprevent degradation, the end faces of the laser were provided withprotective films. The shape of a laser beam was almost oval as indicatedby 54, 54′. As shown in this figure, an examination was made as to twocases. In one case, the direction of the minor axis of about 1 μm wasalmost parallel to the record track 55, 55′ and in the other case, thedirection of the minor axis was perpendicular to the record track 55,55′. The flying height was 10 nm.

Incidentally, the recording element shown in FIGS. 6A and 6B, FIGS. 7Aand 7B and FIGS. 8A and 8B was first used corresponding to the recordingelement 53, 53′. In the embodiment shown in FIGS. 6A and 6B, a36Ni-62Fe-2Nb film with a resistivity of 75 μΩcm and a film thickness of1.8 μm was formed as 62 and 64 and a 45Ni55Fe film with a resistivity of45 μΩcm and a film thickness of 1.8 μm was formed as 61 and 63. As shownin FIG. 6A, a track width T_(ww) of 0.53 μm was obtained in the waferstate by performing trimming through the use of ion milling, the RIEmethod, etc. Furthermore, a magnetic core length l₁ of 35 μm, a magneticpole length l₂ of 50, 55, 60 or 65 μm, a number of turns of Cu coil of15, and a recording gap length GI of 0.19 μm (material for the gap:Al₂O₃-5% SiO₂) were obtained.

In another embodiment shown in FIGS. 7A and 7B, an 80Co-10Ni-10Fe-1Pfilm with a resistivity of 20 μΩcm and a film thickness of 0.7 μm wasformed as 72 and 74 and a 75Co-10Ni-10Fe-5P film with a resistivity of65 μΩcm and a film thickness of 1.5 μm was formed 71 and 73. As shown inFIG. 7A, a track width T_(ww) of 0.47 μm was obtained in the wafer stateby performing fabrication and, furthermore, a magnetic core length l₁ of33 μm, a magnetic pole length 1₂ of 45, 50, 55, 60 or 65 μm, a number ofturns of Cu coil 116 of 15, and a record gap length Gl of 0.18 μm(material for the gap: Al₂O₃-5% SiO₂) were obtained.

In a further embodiment shown in FIGS. 8A and 8B, a multilayer film,obtained by alternately depositing an 90Fe-5Al-5Si film with aresistivity of 20 μΩcm and a film thickness of 0.1 μm and a 10-nm thickZrO₂ layer to form a total of ten layers, was formed as 82 and a75Co-15Ta-10Zr film with a resistivity of 100 μΩcm and a film thicknessof 1.5 μm was formed as 118. As shown in FIG. 8A, a track width T_(ww)of 0.5 μm was obtained in the wafer state by performing trimming by theFIB method and, furthermore, a 44Ni-56Fe film with a resistivity of 45μΩcm and a film thickness of 1.9 μm was formed with an end width of 0.7μm. The magnetic core length l₁ was 33 μm, the magnetic pole length 1₂was 40, 50, 55, 60 or 65 μm, the number of turns of Cu coil 116 was 11,and the record gap length GI was 0.20 μm (material for the gap: Al₂O₃-7%SiO₂). Incidentally, still further embodiments with the same magneticcore length, but with different magnetic pole lengths of 55, 60 and 65μm were also fabricated in addition to the above embodiments.

In all of these embodiments, the read element was fabricated as follows.A magnetically free NiFe/CoFe film (5 nm), a CuNi film (2.5 nm), amagnetically fixed layer of CoFe/Ru/CoFe film (5 nm) and an MnIr (13 nm)film were formed one after another and a rectangular pattern wasobtained. After that, a permanent magnet of Co75-Ni₁₅—Pt10-5% HfO₂ (12nm) and an electrode film of Nb-T1 (90 mm) were arranged on both ends ofthe pattern and a giant magnetoresistive element with a track width of0.41 μm, which is determined by the spacing between electrodes, wasprovided on a 2.1-μm thick plated shielding film of Ni80-Fe20 throughthe gap, thereby giving this structure to the read element (total shieldgap: 0.8 μm, material for the gap: Ta₂O₅). The read portion thusfabricated was used as the magnetic head element of the presentinvention. In this example, an RW-IC fabricated by the scaledown processfor 0.25 μm was mounted on the integrated circuit suspension thatsupports the above head. A signal processing LSI separately installedwas of the EEPRM type formed by the scaledown processes for 0.25 and 0.2μm.

The following media of the same structure as those shown in FIG. 1 werenewly fabricated in addition to the media shown in Table 1. An amorphousmagnetic material, which contains at least one metal element selectedfrom the group consisting of Co, Fe and Ni as a primary component, atleast two elements selected from a second group consisting of Cr, Mo, W,V, Nb, Ta, Ti, Zr, Hf, Pd, Pt, Rh, Ir and Si, and a least one elementselected from a third group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu,Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Bi, Sb, Pb, Sn, Ge and B, was formed ona non-magnetic substrate of Si with a diameter of 3.5, 2.5, 1.8, 1 inch,etc. The numeral 14 indicates a protective film made of N-added C,H-added C, BN, ZrNbN, AlN, SiAlOH, etc. The numeral 15 indicates alubricant of perfluoro-alkyl-polyether having adsorptive or reactive endgroups such as OH and NH₂, an organic fatty acid, etc. Between thenon-magnetic underlayer 12 and the hard magnetic layer 13, there may beprovided a second non-magnetic underlayer whose composition is furtheradjusted. When the above magnetic layer is divided by a non-magneticintermediate layer, which contains as a main element at least oneselected from the group consisting of Cr, Mo, V, Nb, Ta, Zr, Hf, Ti, Ge,Si, Co, Ni, Al, Zn, C and B singly or Cr—Ti10, Mo—Cr10, W—Si5, Ta—Si5,Nb—Zr10, Ta—Cr5, Zr—Hf10, Hf—Ti5, Ti—Si10, Ge—Pt5, Si—Ru11, Co—Cr3,C—N10, B—N10, etc., noise decreases almost in proportion to the squareroot of the total number of magnetic. Therefore, this is morepreferable.

This example is explained below in further detail. A magnetic disk wasfabricated by forming a non-magnetic underlayer of SiN, Cr alloy, etc.on an Si disk with a diameter of 1.8″ and then further depositing oneafter another an amorphous magnetic layer of TbFeCo, DyFeCo, NdTbFeCo,TbFeCoNb, TbFeCoPt, etc., an 8-nm thick protective film of carbon towhich 15% N is added, and a 5-nm thick lubricating film ofperfluoro-alkyl-polyether having end groups of —OH.

Both the underlayer of SiN, Cr alloy, etc. and the magnetic layer wereformed by means of an RF magnetron sputtering device using Ar gas andthe protective film was further formed in an N₂ gas atmosphere by theplasma-induced reactive magnetron sputtering method. On that occasion,the Ar pressures was from 0.5 to 10 mTorr, the substrate temperatureswas from 50 to 200° C., and the deposition rate was about 3 nm/s. In theunderlayer, Al₂O₃ and Cr—Ti were used as a single layer or two layerscomposed of dissimilar underlayers in addition to SiN and Cr. Thus,samples of different underlayer compositions were prepared. The totalfilm thickness of the underlayer was from 10 to 200 nm, that of theamorphous magnetic layer of TbFeCo, DyFeCo, NdTbFeCo, TbFeCoNb,TbFeCoPt, TbFeCoBi, etc. was from 20 to 750 nm, and that of theprotective film was 8 nm. Compositions with a higher Fe concentrationthan usual compositions used in magneto-optic disks permit greatsaturation magnetization and allow the film thickness of a medium to berelatively reduced. Therefore, this was favorable in terms of magneticrecording. Magnetic disks of the present invention made by way of trialin Example 3 are shown in Table 2.

TABLE 22 Ar Temperature Orientation Under Sputtering of of layerpressure substrate magnetic Magnetic Layer (nm) (nm) (MTorr) (° C.)layer 1 CoTb₁₀Zr₃Pt₁₅ (200) CrTi(40 0.2 200 in-plane 2FeCo₁₀Tb₁₅Pt₅Cr₂(270) CrTa(60) 0.2 180 perpendicular 3 FeCo₅Tb₂₀Si₅Pd₂(350) Al₂O₃ (100) 0.5 150 perpendicular 4 FeCo₅Tb₇Bi₅Ta₂Cr₁(20) CrV (30)0.5 100 perpendicular 5 FeCo₁₀Tb₁₅Nb₅Mo₂(270) Cr (20) 1.0 150perpendicular 6 FeCo₁₅Dy₁₅Bi₅V₂Ti₂(450) ZnS (30) 1.0 200 perpendicular 7FeCo₁₀Tb₃₀Ge₅Zr₂Ir₂(570) Wti (10) 2.0 50 perpendicular 8FeCo₁₀Nd₁₅Pt₂W₂(370) MoSi (20) 2.0 200 perpendicular 9FeCo₅Dy₁₀Lo₅Rh₂Hf₂(45) NiCr (30) 5.0 50 perpendicular 10FeCo₁₃Tb6Ce₅Pt₂Tr₂(350) CoCr (20) 5.0 100 perpendicular 11FeCo₁₀Tb₁₅Pt₂Ta₂(270) TaCr (30) 0.2 150 perpendicular 12FeCo₇Dy₂₅Nd₅(350) MoCr (90) 0.2 175 perpendicular 13FeCo₃₆Tb₁₆Nd₁₃Pt₂V₃(650) TaCr (65) 0.5 150 perpendicular 14FeCo₄₂Nd₂₀Pr₅Pt₂Ti₂(750) V (40) 0.5 181 perpendicular 15FeCo₁₆Tb₂₆Eu₅Pt₄Pd₂(750) Nb (40) 1.0 124 perpendicular 16FeCo₁₃Tb₂₃Nb₁W₂(650) TiCr (50) 1.0 54 perpendicular 17FeCo₁₀Tb₂₀Pm₃Si₂W₂(590) WCr (50) 2.0 165 perpendicular 18FeCo₁₅Dy₁₅Gd₅Ir₂W₂(580) TiTa (60) 2.0 65 perpendicular 19FeCo₁₅Tb₂₂Rh₂Zr₂(570) TiV (50) 5.0 145 perpendicular 20FeCo₁₀Nd₁₅Pd₂Si₂(690) TiPt (50) 5.0 116 perpendicular 21FeCo₁₂Tb₂₈Iio₅Ir₂Ti₂(680) TiPb (50) 10 195 perpendicular 22FeCo₁₀Tb₂₂Er₅Zr₂V₂(530) TiNb (60) 10 121 perpendicular 23FeCo₁₀Tb₂₂Tm₅B₂Mo₂(570) SiN (60) 10 101 perpendicular 24FeCo₁₀Tb₂₂Yb₅Cr₂W₂(480) C (50) 1.0 95 perpendicular 25FeCo₁₀Tb₂₂Lu₅(500) Ge (50) 1.0 81 perpendicular

In all of the media of this example, the magnetic films are made ofamorphous materials with an in-plane or a perpendicular anisotropy.Especially, in perpendicular media, the noise coefficient is generallynegative. In media with a coercive squareness of not less than 0.95,noise was especially low and this was preferable. In all cases, theabsolute value of normalized noise coefficient per recording density wasnot more than 2.5×10⁻⁸ (μVrms)(inch)(μm)^(0.5)/(μVpp). Under the sameconditions as with the above third example in Table 2, media of anotherembodiment were fabricated with a magnetic layer made of Cr, Mo, W, V,Nb, Ta, Zr, Hf, Ti, Ge, Si, Co, Ni, C or B singly or a magnetic layermade of one of the above elements but divided into two layers by anintermediate non-magnetic layer made of Cr—Ti10, Mo—Cr10, W—Si5, Ta—Si5,Nb—Zr10, Ta—Cr5, Zr—Hf10, Hf—Ti5, Ti—Si10, Ge—Pt5, Si—Ru11, Co—Cr30—Pt5,C—N10, B—N10, S—N50, etc. In all these media, noise decreased to thelevels of from 65 to 75%. This was especially preferable.

To fabricate a magnetic disk device, 10 media shown in Table 1 or Table2 were mounted as 31 and 20 heads of each of the above embodiments weremounted as shown in FIGS. 3A and 3B. Recording was performed by magneticfields from the magnetic heads while controlling the coercive force ofmedia by the local heating effected by means of a laser duringinformation recording. The number of revolutions was from 20,000 to30,000 rpm and temperature rises in the recording positions of media bylocal heating were optimally controlled in the range of about 50° C. to300° C. Under this method, recording conditions are susceptible tofluctuations in external temperature. Therefore, it was desired tooptimize laser power by performing trial writing in the initial stage ofrecording and at prescribed intervals of time after operation.

In all the media, when the major axis of laser almost coincided with thetrack direction, interference with adjoining tracks was small and thebest characteristics were obtained. Even in a case where the minor axiscoincided with the track direction, however, high densities about twicethe density in conventional technology could be realized. Morespecifically, areal densities of not less than 7 Gb/in² could beachieved at 50 MB/s for the media of the embodiments shown in Table 1and areal densities of not less than 15 Gb/in² could be achieved at 50MB/s similarly for the media of the embodiments shown in Table 2. In adevice provided with the above media having a magnetic layer dividedinto two layers, recording density could be improved by about 20%. Thiswas especially preferable. Incidentally, a read signal processing LSIfabricated by the process for 0.2 μm was about 30% favorable in terms ofpower consumption and processing speed.

EXAMPLE 4

The heads of Example 3 were also adopted as the magnetic heads ofExample 1 and Example 2 and evaluated. In all of these heads of Example3, operation of the device at areal densities of not less than 7 Gb/in²and data transfer rates of not less than 60 MB/s were verified andcharacteristics equal to or better than those obtained in Example 1 andExample 2 were obtained. This was especially preferable in terms of datatransfer rate. When the magnetic pole length was 55, 60, and 65 μm,recording and reading were possible at a data transfer rate of from 60to 65 MB/s. However, when the magnetic pole length was not more than 50μm, data transfer rate of from 66 to 70 MB/s was possible. This wasespecially preferable. It was ascertained by a computer simulation thatit is important to reduce not only the magnetic core length l₁, but alsothe magnetic pole length l₂ because eddy currents are generated in therear part of a magnetic pole. The R/W-IC portion was separated from thesignal processing portion and formed by the scaledown process for notless than 0.35 μm. After that, this R/W-IC portion was mounted on theintegrated circuit suspension of the present invention in whichthin-film lead layer and an insulating layer are formed directly on aplate spring by the thin film process, or on a wiring FPC, and thedistance from the head was set at not more than 1 cm. In this case,degradation of signals was not practically observed and an improvementin data transfer rate of not less than 50 MB/s was observed compared toa case in which an R/W-IC was integrated with a signal processingcircuit and installed on a circuit board as conventionally. This wasespecially preferable.

The above Examples 1 to 4 represent typical inventions disclosed in thepresent invention and examples that can be easily analogized by thoseskilled in the art also included in the scope of the present invention.Similar effects are obtained from the RF magnetron sputtering method,ECR sputtering method and helicon sputtering method, for example.Furthermore, similar effects are obtained form the oblique-evaporationmethod in an oxygen atmosphere and the ionized cluster beam method andalso by changing the incidence position corresponding to each radius ofa disk. It is needless to say that similar effects are obtained byinstalling a Peltier-effect element in the head and performing heating.Furthermore, the magnetic recording medium, head and device disclosed inthis invention enable magnetic recording and reading in high datatransfer rate at not less than 50 MB/s to be performed at a recordingdensity of not less than 5 Gb/in². Therefore, high data transfer rateand large-capacity magnetic recording and reading devices in whichmagnetic tapes, magnetic cards, magneto-optic disks, etc., are used asthe magnetic recording media of the present invention, are also includedin the scope of the present invention.

As mentioned above, the use of the magnetic recording medium andmagnetic recording and reading device of the present invention, for thefirst time, enables high data transfer rate and large-capacity recordingand reading to be performed. As a result, magnetic recording and readingdevices with very strong product competitiveness can be realized.

1. A magnetic recording and reading device which comprises: a magneticrecording medium having a substrate and at least one magnetic recordinglayer formed above the substrate; a magnetic head comprising a recordinghead having an upper magnetic core and a lower magnetic core with amagnetic core length l₁ of not more than 35 μm, a reading head providedwith a read element having a track width of not more than 0.9 μm, and aheat-generating portion which enables heating of the magnetic recordingmedium; and a R/W-IC; wherein the at least one magnetic recording layercontains (1) at least one metal element selected from a first groupconsisting of Co, Fe and Ni as a primary component, (2) at least twoelements selected from a second group consisting of Cr, Mo, W, V, Nb,Ta, Ti, Zr, Hf, Pd, Pt, Rh, Ir and Si, and (3) at least one elementselected from a third group consisting of La, Ce, Pr, Nd, Pm, Sm, Eu,Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Bi, Sb, Pb, Sn, Ge and B; and whereinthe magnetic head is configured to perform magnetic recording on themagnetic recording medium by application of a magnetic field from themagnetic head while the heat-generating portion of the magnetic headlocally heats the magnetic recording medium so as to enable a change ofthe coercive force of the magnetic recording medium during theinformation recording, and to perform reading of the magnetic recordinginformation with the aid of the reading head.
 2. A magnetic recordingand reading device according to claim 1, wherein the at least onemagnetic recording layer includes amorphous magnetic material.
 3. Amagnetic recording and reading device according to claim 1, wherein themagnetic recording medium has a perpendicular anisotropy magneticrecording layer.
 4. A magnetic recording and reading device according toclaim 1, wherein the heat-generation portion includes a semiconductorlaser chip which performs the heat-generation.
 5. A magnetic recordingand reading device according to claim 4, wherein the semiconductor laserchip provides heat-generation light which has a substantially ellipticalcross-section of which a major axis is almost the same as a recordedtrack width.
 6. A magnetic recording and reading device according toclaim 1, wherein a range of heating temperature is about 50° C. to 300°C.
 7. A magnetic recording and reading device according to claim 1,wherein the substrate is a non-magnetic Si.
 8. A magnetic recording andreading device according to claim 1, wherein the recording head ismounted on an integrated circuit suspension so that a total inductanceis reduced to be not more than 65 nH and has a magnetic core beingformed by a magnetic film having a resistivity exceeding at least 50μΩcm or by a multilayer film composed of a magnetic film and aninsulating film.
 9. A magnetic recording and reading device according toclaim 1, wherein the R/W-IC has a line width of not more than 0.35 μm.10. A magnetic recording and reading device according to claim 1,wherein the magnetic recording layer is a multilayer composed of amagnetic thin film and a non-magnetic intermediate layer comprising atleast one kind of element selected from the group consisting of Cr, Mo,W, V, Nb, Ta, Xr, Hf, Ti, Ge, Si, Co, Ni, C and B as a primarycomponent.
 11. A magnetic recording and reading device according toclaim 1, wherein the read element is a giant magnetoresistive element ora tunneling-magnetoresistive element.
 12. A magnetic recording andreading device according to claim 4, wherein the recording head performstrial writing in an initial stage of recording and at prescribedintervals of time after operation.
 13. A magnetic recording and readingdevice according to claim 1, wherein the magnetic head is configured toperform magnetic recording and reading of the magnetic recording mediumat a data transfer rate of not less than 50 MB/s and a recording densityof not less than 5 Gb/in².
 14. A magnetic recording and reading deviceaccording to claim 1, wherein the R/W-IC enables control of the magnetichead including the heat-generating portion thereof.
 15. A magneticrecording and reading device comprises: a magnetic recording mediumhaving a substrate and a thin magnetic recording layer formed above thesubstrate; a magnetic head having a recording head; and a R/W-IC;wherein the recording head has an upper magnetic core and a lowermagnetic core with a magnetic core length l₁ of not more than 35 μm, anda heat-generating portion which enables heating of the magneticrecording medium; wherein the reading head has a read element having atrack width of not more than 0.9 μm; wherein an absolute value ofnormalized noise coefficient per recording density of the magneticrecording medium is not more than 2.5×10⁻⁸(μVrms)(inch)^(0.5)/(μVpp);and wherein the magnetic head is configured to perform magneticrecording on the magnetic recording medium by application of a magneticfield from the magnetic head while the heat-generating portion of themagnetic head locally heats the magnetic recording medium so as toenable a change of a coercive force of the magnetic recording mediumduring the information recording, and to perform reading of the magneticrecording information with the aid of the reading head.
 16. A magneticrecording and reading device according to claim 15, wherein the magnetichead is configured to perform magnetic recording and reading of themagnetic recording medium at a data transfer rate of not less than 50MB/s and a recording density of not less than 5 Gb/in².
 17. A magneticrecording and reading device according to claim 15, wherein the R/W-ICenables control of the magnetic head including the heat-generatingportion thereof.